The status of hospital patients is routinely monitored by obtaining and testing human fluids (blood, urine, spinal fluid, etc.). Testing is typically performed at a centralized location, such as a clinical laboratory.
A great volume of human fluids, and in particular, human serum, is handled daily by hospital clinical chemistry laboratories. Typically, each admitted patient has at least a tube of blood collected every day by a phlebotomist.
In a clinical laboratory, these blood samples are processed by first centrifuging the unopened tube to separate the cells from the serum or plasma. Thereafter, the tube is opened by removing the rubber stopper by hand. To maintain the separation, plastic inserts can be manually pushed down into the serum to a level just above the packed cells.
The tubes are placed in a standard test tube rack and delivered to a technologist for automated analysis. At this point, the technologist running the machine pipettes serum from the top of tube into a small sample cup. The sample cup is then placed on the instrument and processed.
This intensive handling of potentially infectious human fluids is not without health risk. The Occupational Safety and Health Administration (OSHA) estimates that over five million health workers, including hospital laboratory workers, are exposed to bloodborne-pathogen infections in the work place annually. The pathogen responsible for the overwhelming majority of infections is the hepatitis B virus (HBV). The Center for Disease Control (CDC) estimates there are twelve thousand cases of HBV infection among health workers each year. Of these cases, over five hundred require hospitalization and approximately two hundred and fifty of these patients die (i.e. from fulminant hepatitis, cirrhosis or liver cancer). See Guidelines for Prevention of Transmission of HIV and HBV to Health-Care and Public Safety Workers, CDC (February 1989). Most full time laboratory employees contract hepatitis at least once during their career. Indeed, up to one third of all health care workers show serological evidence of a previous HBV infection. Id.
Following the recognition of the Acquired Immunodeficiency Syndrome (AIDS), clinical laboratories have moved away from using plastic inserts to maintain the separation of cells from serum. A "gel" is now available that is in the empty tube at the time the blood is drawn. When the tube is centrifuged the cells go below the gel while the serum remains above. While the separation can be maintained in this manner without as much sample handling, this does not reduce the handling of the technologist at the point of analysis. Technologists who come into contact with the fluids from AIDS patients must be aware that infectious virus can persist in a liquid or dried state for prolonged periods of time, possibly even at elevated temperatures. Resnick et al., JAMA 255:1887 (1986).
Preventative measures such as gloves and eye-wear are not complete solutions to the problem. Accidents in the laboratory or clinic typically involve exposure over a larger portion of the body and disease can be transmitted through the skin and mucous membranes. Morbidity and Mortality Weekly Report 36:285 (1987).
Clearly, there remains a need for a more adequate solution to bloodborne-pathogen infections in the work place. Such a solution should serve as a protection against a wide range of pathogens. Furthermore, the mechanics of the solution should not unduly interfere with laboratory operations.